1. Field of the Invention
The present invention relates to a multilayered ceramic capacitor and a mounting structure of a circuit board having a multilayered ceramic capacitor mounted thereon.
2. Description of the Related Art
A multilayered ceramic capacitor, a type of multilayered electronic chip component, is a chip type condenser mounted on printed circuit boards of various electronic products, such as, image devices including a liquid crystal display (LCD) and a plasma display panel (PDP), a computer, a personal digital assistant (PDA), a mobile phone, and the like and implementing charging or discharging of electricity therein.
A multilayered ceramic capacitor (MLCC) may be used as components in various electronic products due to the advantages of compactness, high capacitance, and ease of mounting.
A multilayered ceramic capacitor may have a structure in which a plurality of dielectric layers and a plurality of internal electrodes having different polarities, disposed between the dielectric layers, are alternately laminated with each other.
Since dielectric layers have piezoelectric properties and electrostrictive properties, a piezoelectric phenomenon may occur, thus causing vibrations among the internal electrodes when alternating current (AC) or direct current (DC) voltage is applied to the multilayered ceramic capacitor.
Such vibrations are transferred to a printed circuit board on which the multilayered ceramic capacitor is mounted, through external electrodes of the multilayered ceramic capacitor, and the entire printed circuit board becomes an acoustic reflection surface to generate vibration sound as noise.
The vibration sound may be within an audible frequency range of 20 to 20000 Hz, and this vibration sound may give an unpleasant feeling to listeners and is known as acoustic noise.
In order to reduce acoustic noise, studies have been made on the mounting direction in which internal electrodes formed in the multilayered ceramic capacitor are mounted on a printed circuit board.
More specifically, acoustic noise is further reduced when the multilayered ceramic capacitor is mounted on a printed circuit board such that internal electrodes have directivity perpendicular with respect to the printed circuit board than in the case in which the multilayered ceramic capacitor is mounted on the printed circuit board such that the internal electrodes have directivity horizontal with respect with the printed circuit board.
However, even though the acoustic noise is measured by mounting the multilayered ceramic capacitor on the printed circuit board such that the internal electrodes have directivity perpendicular with respect to the printed circuit board, the noise has a predetermined level. Therefore, new measures of reducing acoustic noise are required.